Sunburn protein found, could lead to broader pain treatments

A sunburn’s hot and aching soreness is difficult to ease, even after slathering on aloe vera, and especially when tossing and turning at night. Now researchers say they’ve found a protein responsible for this inflammatory pain. Targeting this molecule could eventually lead to new ways to relieve not only soreness from too much time at the beach but also other types of chronic pain.

To reach their conclusion, researchers burned tiny patches of skin on human volunteers with UVB light (the type of radiation classically associated with skin cancer) and, via biopsy, assessed levels of more than 90 proteins at the peak of the sunburn’s sensitivity, about one to two days after the initial burn.

Levels of one protein, called CXCL5, were found to be especially high. Scientists inspected the skin of sunburned rats and found elevated CXCL5 levels there too. Further, when the scientists injected CXCL5 into otherwise healthy rats, those animals became hypersensitive to pain.

But the pain could be blocked. Researchers injected an antibody targeting CXCL5 into sunburned rats; those rats were able to better withstand the pain from poking their hindpaws. The results were published online Wednesday in Science Translational Medicine.

The researchers believe identifying the protein — and conducting similar human and rat studies on pain — could lead to more clinical treatments for chronic pain.

Said Steve McMahon, a pain researcher from King’s College London who co-led the study, in a press release:

“These findings have shown for the first time the important role of this particular molecule in controlling pain from exposure to UVB irradiation. But this study isn’t just about sunburn -- we hope that we have identified a potential target which can be utilised to understand more about pain in other inflammatory conditions like arthritis and cystitis.”